Monday, September 22, 2008

High Performance on Wall Street 2008

A freshly rebranded Catalyst Accelerated Computing went to the High Performance on Wall Street conference today. The usual suspects were present. Speedup results all seemed to match the gender ratio at supercomputing conferences.

FPGAs got bashed in an early session. "It's hard to find people to program FPGAs" came up at least twice during the conference (we consult!). I heard, "threads are the future" ... oy. After the earily morning thread-love-fest, the acclerator panel defended the honor of the gate array well.

Technical stuff that irked me:

Multithreading and multicore aren't the same thing. Multicore processors can use multiple processes with explicit pipes or they can use multiple threads with a global memory coherency protocol. Multiple processes with pipes between them is the dataflow or "streaming" model, like a spreadsheet or like "ls -Al | grep foo > bar", while the multi-threading model should be avoided like sub-prime mortgages for the same reason (they cause your system to crash in mysterious ways).

Multithreading is the use of multiple instruction streams sharing a global address space. It was originally a method of hiding latency by transfering the context of a core to a different thread when you were waiting for I/O or memory. Intel cores support "hyperthreading" which switches context between two threads and makes it seem like it has two cores. This allows the core to share a global memory space and hide memory access latency which is large compared to the clock rate. Cores can have a lot of threads: Sun's open-source Sparc core supports 32 native threads.

Power consumption P = fCV^2. The power voltage (V) is generally linearly dependent on f (frequency) because we can use less potential to switch at slower frequency resulting in the "cubic rule of thumb" relating clock-speed and power. If we use twice the area and half the frequency to do the same work, then switched Capactiance (C) is 2x while f*V^2 is 1/8, leading to the rule-of-thumb quadratic power savings from parallelism (see Chapter 11.7 of Anantha's book "Digital Integrated Circuits").. Leakage is the dominating factor now though and slower switching circuits can operate with higher threshold voltage to lower leakage if your device supports dynamic threshold scaling (like the Stratix IV from Altera will).

The better reason why FPGAs dominate in power performance is becaues of the efficient total distance of data-flow, aka much lower capacitance to move data. As the number of cores increases, there is an O(N^(3/2)) relationship between the number of cores and the degree to which a design can be optimized for process locality (see "locality optimization"). This is why place-and-route is so important for FPGAs.

Now for the fun stuff. Buzzword scoreboard from presentations:

{ "Leverage": 17, "Agility": 4, "Low-Latency": 44, "Accelerate": 176, "Eco-System": 8, "Productivity": 191, "Scalability": 83, "Service-Oriented": 17, "Paradigm":16,"Dynamic":55, "Exploit Multicore": 18, "Future-Proof": 4, "Mainstream": 36, "Seamless": 43, "Cloud": 91, "Heterogeneous": 12, "Efficient": 50, "Enabling": 23, "Integrated": 19, "Interoperability": 24, "Realtime": 12, "Reliability": 13, "High-Availability": 33, "Bottleneck": 26 }

Productivity wins.

I'm particularly amused by the frequency of "mainstream." Mainstream on Wall Street today probably means your firm just shut down, merged, or totally changed business models. Happy Monday for a Wall Street Conference!

Coming soon: a business-plan buzzword-compliance checker to determine if your business plan is syntactically correct and give you a score.


amateur said...

I really like your blog, funny, informative and suitably nerdy for someone like me.

Have you actually tried that pickup-line ("I've got a blog about FPGAs")?

Raphael Korsoski

Amir said...

thank you :)

Advice from Yoda: don't "try" pickup lines. Especially ones with acronyms.

Anonymous said...

Your blog is nice. Here in Brazil we don't have much information on FPGAs. Thanks.

Anonymous said...

Is this really the time to try and "sell" anything to wall street?